Inkjet recording medium and inkjet recording method

Abstract

An inkjet recording medium having an ink receiving layer containing an inorganic pigment, starch, and copolymer latex on at least one surface of a base, characterized in that the inorganic pigment contains engineered calcium carbonate and kaolin, an amount of the engineered calcium carbonate is from 50% by weight or more to less than 80% by weight and an amount of the kaolin is from 10% by weight or more to less than 50% by weight with respect to a total amount of the inorganic pigment, and from 1 parts by weight or more to 10 parts by weight or less of an organic pigment having a glass transition temperature (Tg) of 20° C. or more is contained in the ink receiving layer with respect to 100 parts by weight of the inorganic pigment.

We claim: 
     
       1. An inkjet recording medium having an ink receiving layer containing an inorganic pigment, starch, and copolymer latex on at least one surface of a base, characterized in that
 the inorganic pigment contains engineered calcium carbonate and kaolin, an amount of the engineered calcium carbonate is from 50% by weight or more to less than 80% by weight and an amount of the kaolin is from 10% by weight or more to less than 50% by weight with respect to a total amount of the inorganic pigment, 
 wherein the engineered calcium carbonate has a ratio (D75/D25) of a cumulative 75% by weight particle diameter (D75 (μm)) and a cumulative 25% by weight particle diameter (D25 (μm)) measured by an X-ray transmission sedimentation particle size distribution measurement method of 3.0 or less, and 
 the ink receiving layer further contains from 1 part by weight or more to 10 parts by weight or less of an organic pigment having a glass transition temperature (Tg) of 20° C. or more with respect to 100 parts by weight of the inorganic pigment. 
 
     
     
       2. The inkjet recording medium according to  claim 1 , wherein the engineered calcium carbonate has a volume 50% average particle diameter (D50) measured by a laser light scattering method of 0.2 μm or more to 2.0 μm or less. 
     
     
       3. The inkjet recording medium according to  claim 1 , wherein the kaolin has a volume 50% average particle diameter (D50) measured by a laser light scattering method of 0.1 μm or more to 1.5 μm or less. 
     
     
       4. The inkjet recording medium according to  claim 1 , wherein the amount of the kaolin is from 20% by weight or more to 40% by weight or less with respect to a total amount of the inorganic pigment. 
     
     
       5. The inkjet recording medium according to  claim 1 , wherein the copolymer latex contains an acrylonitrile styrene butadiene-based copolymer. 
     
     
       6. The inkjet recording medium according to  claim 1 , wherein white paper glossiness at a light incidence angle of 60 degrees according to JIS Z8741 of a surface of the ink receiving layer is from 25% or more to 50% or less. 
     
     
       7. The inkjet recording medium according to  claim 1 , wherein the inkjet recording medium has air permeability according to J. TAPPI No. 5-2: 2000 of from 5000 seconds or more to less than 11000 seconds. 
     
     
       8. An inkjet recording method for printing an inkjet recording medium with inkjet ink as aqueous pigment ink, wherein
 the inkjet recording medium includes an ink receiving layer containing an inorganic pigment, starch, and a copolymer latex on at least one surface of a base, 
 the inorganic pigment of the ink receiving layer contains engineered calcium carbonate and kaolin, an amount of the engineered calcium carbonate is from 50% by weight or more to less than 80% by weight, and an amount of the kaolin is from 10% by weight or more to less than 50% by weight with respect to the total amount of the inorganic pigment, 
 wherein the engineered calcium carbonate has a ratio (D75/D25) of a cumulative 75% by weight particle diameter (D75 (μm)) and a cumulative 25% by weight particle diameter (D25 (μm)) measured by an X-ray transmission sedimentation particle size distribution measurement method of 3.0 or less, and 
 the ink receiving layer further contains from 1 part by weight or more to 10 parts by weight or less of an organic pigment having a glass transition temperature (Tg) of 20° C. or more with respect to 100 parts by weight of the inorganic pigment, and 
 the inkjet ink contains one or more pigments selected from self-dispersed pigment and pigment containing water insoluble polymer particles, from 10% by weight or more to 46% by weight or less of a water soluble organic solvent A having a boiling point of 230° C. or less, from 0% by weight or more to 5.0% by weight or less of a water soluble organic solvent B having a boiling point of 280° C. or more, and from 44% by weight or more to 70% by weight or less of water. 
 
     
     
       9. The inkjet recording method according to  claim 8 , wherein the printing is performed by one pass printing at a frequency of 20 kHz or more. 
     
     
       10. The inkjet recording method according to  claim 8 , wherein a ratio Y/X satisfies the following formula:
   12×10 −15 ≤Y/X≤11×10 −14  
 
 where X is an amount (g/m 2 ) of the engineered calcium carbonate per unit area of the ink receiving layer and Y is an amount of the water soluble organic solvent A (g/m 2 ) per dot area when the inkjet recording medium is dot printed with the inkjet ink. 
 
     
     
       11. The inkjet recording method according to  claim 8 , wherein the inkjet ink further contains from 0.6% by weight or more to 3.0% by weight or less of a nonionic surfactant. 
     
     
       12. The inkjet recording method according to  claim 8 , wherein the pigment of the inkjet ink contains water insoluble polymer particles. 
     
     
       13. The inkjet recording method according to  claim 8 , wherein the engineered calcium carbonate has a volume 50% average particle diameter (D50) measured by a laser light scattering method of 0.2 μm or more to 2.0 μm or less. 
     
     
       14. The inkjet recording method according to  claim 8 , wherein the kaolin has a volume 50% average particle diameter (D50) measured by a laser light scattering method of 0.1 μm or more to 1.5 μm or less. 
     
     
       15. The inkjet recording method according to  claim 8 , wherein the copolymer latex contains an acrylonitrile styrene butadiene-based copolymer. 
     
     
       16. The inkjet recording medium according to  claim 2 , wherein the kaolin has a volume 50% average particle diameter (D50) measured by a laser light scattering method of 0.1 μm or more to 1.5 μm or less. 
     
     
       17. The inkjet recording medium according to  claim 2 , wherein the amount of the kaolin is from 20% by weight or more to 40% by weight or less with respect to a total amount of the inorganic pigment.